1. Field of the Invention
The invention relates to a new microbiological process for the production of 6-hydroxypicolinic acid, starting from 2-cyanopyridine, as well as to new microorganisms suitable for the process.
2. Background Art
It is known that microorganisms of the genus Bacillus hydroxylate picolinic acid to 6-hydroxypicolinic acid [O. Shukla and S. M. Kaul, Indian J. of Biochemistry and Biophysics, (1973), Vol. 10, pages 176 to 178; O. Shukla et al., Indian J. of Biochemistry and Biophysics, Vol. 14, (1977), pages 292 to 295]. A great drawback of this process is that the further metabolization of the 6-hydroxypicolinic acid can be stopped only with the inhibitor sodium arsenite, and, thus, the growth of the microorganisms also is inhibited Another drawback is that 6-hydroxypicolinic acid is not exclusively formed, but instead a mixture of 3,6-dihydroxypicolinic acid and 6-hydroxypicolinic acid results.
R. L. Tate and J. C. Ensign, Can. J. Microbiol., Vol. 20, (1974), pages 695 to 702, describes the hydroxylation of picolinic acid with microorganisms of the genus Arthrobacter. Drawbacks of this process are that these microorganisms cannot use picolinic acid exclusively as a carbon, nitrogen and energy source, but in the hydroxylation, a yeast extract has to be present, which can lead to undesirable impurities of the product. Another drawback lies in the fact that the 6-hydroxypicolinic acid is formed only in the case of low oxygen content, and the microorganisms are not present in the growth phase, and thus little product is formed.